2 Abstract: An experiment was conducted at Agricultural Research Station, Comilla during summer (Kharif) season, 2009 to estimate the proportionate yield and economic loss of sesame due to different management factors and to identify major factors of yield loss reduction of sesame. From the results of the experiment, it was found that the yield reduction of sesame variety BARI Til-3 were reduced over the recommended package of practices by 24.6%, 15.10%, 15.05% and 7.40% from the treatments with delay sowing, no seed treatment, no insect control and no disease control respectively. The highest net return (Tk.18320/ha) was obtained from the treatment with recommended package. The highest economic loss Tk. 11840/- was recorded from the treatment with delay sowing and the second highest economic loss Tk. 6980/- was found from no seed treated plot. The highest yield (1595.67 kg ha ) was found from full package treatment followed by no fungicide 1 treatment (1477.33 kg ha ) and the lowest yield (1201.3 kg ha ) was found from delay sowing treatment. 11 To minimize the yield gap and economic loss of sesame, full Package of management Practices should be apply.